In recent years, IP (Internet Protocol) telephone systems for VoIP (Voice over IP) over intranets and the Internet have been spreading rapidly in offices.
On the other hand, mobile telephones incorporating two telephone modules, one for communication over a mobile communication network and the other for communication over a wireless LAN, have appeared on the market, as exemplified by FOMA™ mobile telephones.
Japanese Unexamined Patent Publication JP H 11-88499-A (corresponding to JP Patent 2931276-B and U.S. Pat. No. 6,151,493A) published on Mar. 30, 1999 by Sasakura et al. describes an apparatus for prohibiting the use of a mobile or cellular phone. The apparatus can disable a cellular phone or any other device if it separates more than a predetermined distance from the user, and at the same time give a warning to the user. It includes an identification signal transmission unit and a use prohibition mode canceling unit attached or mounted to the cellular phone. Each unit has a transmitter and a receiver. The receiver of the canceling unit receives an ID code signal from the transmission unit and produces, based on the ID signal received, a use prohibition canceling signal. The canceling unit returns a confirmation signal to the transmission unit. If the two units separate more than a predetermined distance from each other, the levels of the ID signal and the confirmation signal received by the respective units drop below a predetermined value. Thus, the canceling unit stops producing the canceling signal to disable the cellular phone, while the transmission unit sounds an alarm.
Japanese Unexamined Patent Publication JP 2003-32261-A published on Jan. 31, 2003 by Ayazuka et al. describes a communication system. In this system, a contactless IC card for communicating with a contactless reader/writer of a personal computer via electromagnetic waves is incorporated in each mobile telephone. When the user brings the mobile telephone into the vicinity of the PC, and the contactless IC card receives the electromagnetic waves radiated from the contactless reader/writer, the mobile telephone sends the card ID of the contactless IC card to the personal computer. The card ID includes the Bluetooth device name of another party to communicate with after the personal computer has established synchronization within a piconet, and the personal computer identifies the communicating party based on that name.
Japanese Unexamined Patent Publication JP 2004-235713-A published on Aug. 19, 2004 by Mineo describes an information providing system, which can provide information that matches the area where the mobile communication terminal is located and also can handle incoming calls and electronic mail in real time, while minimizing the connection standby time that consumes large standby power. The information providing system comprises an RF ID reader which reads the terminal identification information of the mobile communication terminal by transmitting a radio wave to an RF ID tag attached to the mobile communication terminal in a connection standby mode with minimum power consumption, and an information providing server which provides information to the mobile communication terminal via a first communication means. The RF ID reader includes an identification information transmitting means. The information providing server includes an identification information receiving means, a terminal identifying means, an area identifying means, and an information providing means.